The finding is significant in the world of genetics because it ties heart disease risk to the male Y chromosome. Previous studies have suggested that the Y chromosome, which carries relatively few genes, has little to do with inheritance beyond conferring male sex characteristics.

“It gives a completely new role for the Y chromosome,” says Lisa Bloomer, MSc, who made the discovery as a third-year PhD student in the department of cardiovascular sciences at the University of Leicester in the U.K. “It changes a lot of how we see genetics and the sex chromosomes and how important they are.”

The Y Chromosome and Heart Disease

For the study, which is published in The Lancet, an international team of researchers analyzed DNA from more than 3,000 men in the U.K.

In particular, they looked at 11 regions on the Y chromosome. Because the Y chromosome has not changed much over time, scientists can use these regions to determine a person’s ancestry. In genetics, people with shared ancestry belong to the same haplogroup. There are thought to be about 30 haplogroups worldwide.

Researchers found that men who developed heart disease were more likely to belong to the same haplogroup -- haplogroup I -- compared to men who stayed healthy. In fact, being a member of haplogroup I raised a man’s risk for heart disease by about 50% compared to men of different backgrounds.

Haplogroup I was the third most powerful predictor that men would develop heart disease, behind their HDL, or “good,” cholesterol levels, and whether or not they were taking cholesterol-lowering drugs. Experts estimate that about 20% of men in Europe and 10% of men in the U.S. belong to haplogroup I.